I. Field of the Disclosure
The technology of the disclosure relates generally to electromagnetic interference (EMI), and particularly to mitigating effects of such EMI.
II. Background
Mobile computing devices, such as mobile phones and computer tablets, have become increasingly prevalent in contemporary society. These mobile computing devices commonly include multiple circuits that must operate concurrently for successful use of everyday functions. For example, a mobile computing device may be used to make phone calls or send e-mail messages via a wireless modem. The same mobile computing device may also perform other functions using function-specific circuits, such as taking pictures with an integrated camera or viewing a video on an integrated display.
In this regard, each function-specific circuit communicates with a central processor configured to execute instructions related to such functions. More specifically, data and clock signals are exchanged between each circuit and a central processor during function execution. As the frequency of such signals increases, a greater volume of electromagnetic emissions is generated at each clock edge. This increase in electromagnetic emissions causes electromagnetic interference (EMI) that degrades the performance of other circuitry within the mobile computing device.
Additionally, continued miniaturization of mobile computing devices, combined with increased frequencies, further exacerbates the effects of EMI. In particular, as the circuit area within a mobile computing device decreases, circuit elements are placed closer together. This closer proximity of circuit elements increases the effects of EMI generated by the greater electromagnetic emissions resulting from higher frequencies. EMI can also be generated by low frequency signals. Such low frequency signals typically generate EMI at direct or indirect harmonics of a low frequency signal, or may generate intermodulation products with other signals in the mobile computing device. Therefore, it would be advantageous to provide designers with additional tools to mitigate the effects of EMI within mobile computing devices as frequency ranges continue to increase while device sizes decrease.